1. Field of the Invention
The present invention relates generally to a hand tool, and more particularly to a ratchet wrench.
2. Description of the Related Art
Ratchet wrench is a hand tool which allows user to tighten or loosen fasteners, such as nuts and bolts, quickly without having to engage and disengage the fastener repeatedly. A conventional ratchet wrench usually is provided with a ratcheting mechanism. While one turns the wrench in one direction, the ratcheting mechanism transmits the force to drive the fastener, which engages the wrench, and while the wrench is tuned in the opposite direction, the ratchet does not turn the fastener which allows the wrench to be re-positioned for another turn. The conventional ratcheting mechanism usually has a paw and a gear, and there is a gap between the paw and the gear for the reverse turning. However, this gap leads an invalid distance in the beginning while the wrench is turned to drive the fastener. In addition, there is a gap between a rod of the wrench and a socket which engages the rod also, and this gap increases the invalid distance. The invalid distance is disadvantageous for the ratchet wrench to drive the fastener in a narrow space. An improved ratchet wrench provides a gear with more teeth to reduce the gap between the gear and the paw. However, it is much difficult to manufacture the gear with more teeth, and furthermore, the teeth will be thinner that can't take a larger driving force.
Taiwan Utility Module M311540 disclosed a ratchet wrench to eliminate the gap problem. However, there are too many elements in the wrench to fix the problem, so the cost to manufacture the wrench is high, and the process of manufacture is complex and difficult.